Scrap metal consists of byproducts of steel fabrication containing iron and steel. Scrap is one of the two main sources of metallics in steelmaking and is increasingly proving a great practical value. With the advent of environmental regulations and controls and the economics of energy conservation and recycling, the use of scrap metal in steelmaking is becoming more desirable.
One area where this use is increased is in the use of scrap galvanized steel. This material is less expensive than non-galvanized scrap, but its use also has its drawbacks which can offset the economic advantages of lower cost.
As the galvanized scrap steel is heated and melted, gases are emitted at temperatures in excess of 2800.degree. F. These gases pass to a scrubber system to separate air from the solids present along with the gases. This would constitute spraying water into the hot gases present in the scrubber system to wash out the solids.
The use of scrap galvanized steel poses a problem in that zinc is present in the steel as a result of the galvanizing process. As the galvanized steel is heated, zinc is emitted along with gases and is present as the gases enter the scrubber facility. The zinc is prone to deposition on the metal surfaces in the scrubber system, notably the fan, fan shroud and mist eliminators. This is especially problematic in basic oxygen furnaces (BOF) suppressed combustion (SC) systems where there is a limited amount of oxygen present.
This deposition can be costly as there are necessary frequent shut downs of the fans and mist eliminators for cleaning, both mechanical and chemical. The present inventors have discovered a method for inhibiting this zinc, iron, and mixed zinc-iron deposition while the scrubber system is running during normal steelmaking operations.